Electrical precipitating system



Patented Dec. 6, 1921.

L. W. CHUBB. ELECTRICAL PRECIPITATING SYSTEM. APPLICATION T|LEDA1AR.9.1918. 1,399,422.

A n A44 md F lNvENToR 6W/5 W Chubb .A/L/ ATTORNEY WITNESSESI UNITED STATES PATENT OFFICE.

INGHOUSE ELECTRIC! AND MAN UFA PENNSYLVANIA. Y

CTUBING COMPANY, A. CGBPORATION 0F ELECTRICAL PBECIPITATIN'G- SYSTEM.

Specification of Letters Patent.

'Patent-ea Deen, 1921.

Application led latch 9, 1918. Serial No. 221,397.

ToaZZ whom t may concern:

Be it known that I, Lnwrs WARRINGTON CHUBB, a citizen of the United States, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in art, as the collecting electrode. When sufficient particles have been thus attracted to the walls of the treating chamber or collecting electrode, the mass thereby formed detaches itself and falls to the bottom of the chamber.

In order to provide such silent electrical discharges from a central discharge electrode and thereby impart charges to the suspended particles, it has hitherto been necessary to impress upon such discharge electrode a potential of very high value. Since it is impractical to generate a directcurrent voltage of suiiiciently high value for such service, the usual practice has been to supply such a precipitating system with a high alternating-current voltage and then rectify the same, by means of a mechanical rectier. The diiiiculties involved in subjecting mechanical rectifiers to service conditions requiring the use of'such high voltages are numerous and well known, and it is highly desirable to avoid the use Aof the same, if possible.

By my invention, I, therefore, propose to utilize the system herein described in which a relatively low direct-current voltage may be employed in an electrical precipitating system to cause silent electrical discharges from an active electrode and thus avoid the diiliculties attendant upon the use of high voltages.

It 1s well known that, when a negative potential is impressed on a` highly heated or incandescent body, electrons are emitted therefrom and thermionic currents are caused to flow, even though the potential` impressed on such heated electrode has an. extrer ely low value. By thermionic currents I refer to currents which are initiated by the dischargcof electrons from a heated body or by chemical reaction. When such a heated body `is employed as a discharge electrode and is posltioned in a suitable chamber through which a gas or vapor, in which solid or fluid particles are suspended, 1s passing, the electrons emitted by such a heated electrode cause thermionic currents to low across the path of such suspended particles. A negative charge is, thereupon imparted to the suspended particles and, if the wall of the containing member be positively charged, it will act as a collecting electrode and the negatively char ed particles will be attracted thereto. hen a sufficient number of particles have become attached to the collecting electrode, the mass will detach itself and fall to the bottom of the stack.

My invention therefore provides for the use of such an incandescent or heated discharge electrode to obtain such thermionic currents and the subsequent charging and precipitation of the particles in a precipitating system inY which a'relatively low directcurrent potential may be impressed on said system directly from a source of direct-current energy of relatively low voltage Without using any of the intermediate apparatus made necessary by the employment of a high potential alternating current voltage. l

For a better understanding of the nature of my invention, reference may be had to the drawing, in which Figure 1 is an elevational view of a .discharge electrode conforming to my invention and positioned in the treating chamber (shown in section) of a smoke precipitating system, while Figs. 2,

3, 4 and 5are fragmentary elevational views of various modications of my discharge electrode.

Referring more particularly to Fig. l, a smoke-precipitating device is shown atI 1. Within a treating chamber or smoke-stack 2, which constitutes a collecting electrode, is positioned a hollow perforated discharge electrode 3. By means of\the lead wires 5 and 6, a suitable direct-current voltage from ingan incandescent or hot cathode member,

, and causing the emission of electrons which' tory material 12. When current is 'which the ring 9 is give rise to the iow of thermionic currents.

Fig. 2 shows a modiiication of the d ischarge electrode shown in Fig. 1, A1n which the perforations are arranged in an annular manner at spaced intervals along sald electrode.

Fig. 3 represents a discharge electrode which may be used in the preferred embodiment of my invention.

It may often be desirable to so construct the discharge electrode as to shield the flame blasts used to heat the surface of said electrode from the draft caused by the 'gas or vapor pass'n upward through the treating chamber. Vlgith this endin view, I have provided theelectrode with annular recesses 8 in which are disposed rings of refractory material 9 and have further provided the recesses with perforations from which a plurality of flame blasts may impinge on said rings of refractory material to heat the same to a high temperature. Such an annular ring of refractory material, being conducting when very hot or in an incandescent state, will give 0H a relatively large number of electrons which will causethermionic currents to flow quite abundantly even when a relatively low potential gradient is impressed between the discharge electrode and the collecting electrode. More electrons can be produced with the same degree of heat by adding suitable quantities of thoria, zirconia -or other refractory oxids to the material of composed.

Figli shows a further modification of the central discharge electrode the function of which was explained in connection with Fig. l. In this modilication, sections of ranular refractory material are arranged a ong the length of the electrode. Into these are introduced, from the interior of the electrode, a suitable explosive mixture of gas and air, such a mixture producing an incandescent body of very high temperature.

In Fig. 5 a modification of the discharge electrode is shown which has a central conducting member 11 surrounded by refracassed through the conducting member 11, t e refractory material in proximity thereto is raised to a high temperature, causing the' emanation therefrom of electrons and the consequent ow of thermionic currents in the. treating chamber. VThe operation ofg.myzinvent1o 1s as yfollOWSI "`1'. j The gas or vapor to be treated is caused to pass, by' natural.. draft, upward through the treating chamber and between the discharge electrode 3y and the collecting electrodel 2. -`A

low negative potential is then impressed on the 'heated centrah'discharge electrode 3, 'whereupon the thermionic currents which flow between the electrodes impart tothe particlesl suspended in the vapor or gas ,be-

ing treated a negative charge. These particles are then attracted by the positive charge of the collecting electrode 2 sufficient number of them have to the bottom of the chamber.

While I have shown and described a number of embodiments of my invention, it will be apparent to those skilled inthe art that many further modilications may be made therein without departing from the spirit' and, after a lodged thereon, the resultant mass is detached and falls precipitating system,

rents to liow from said discharge electrode upon the application of potential to' the same, said thermal mea-ns consisting of flame blasts to heat said electrode to incandescence in the vicinity of said recesses.

2. In an electrical precipitating system, the combination with a treating chamber and a discharge electrode positioned therein and having a plurality of` annular recesses, of refractory material positioned in said recesses and thermal means for causing thermionic currents to fiow from said refractory material'y upon the application of potential to said electrode, said thermal means consisting of llame blasts produced by, and heating, said refractory material to incandescence.

3. In an electrical precipitating system, the combination with a treating chamber, of a discharge electrode positioned therein, said electrode having sections of refractory material and being provided with perforations through which heat may be applied to said refractory portions for raising said portions to incandescence.

4:. In an electrical precipitating system, the combination with a treatin chamber, of a discharge electrode positioned therein, said electrode having sections of refractory material land being providedy with perforations through which heat may be applied to said refractory portions to cause said portions to emit silent electrical discharges.

5. In an electrical precipitating system,

the combination with a treating chamber, of a discharge electrode positioned therein, said electrode having sections of refractory material and being provided with perforations through which heat blasts may impinge uponsaid refractory portions disposed in proxiniity to said electrode, whereupon said refractory portions are raised to incandescence, thereby causing the llowof tliermionic currents.

6. In an electrical precipitating system, the combination with a treating chamber, of a discharge electrode positioned therein and having a plurality of flame-emitting openings positioned entirely below the electrode surface. Y

7. In an electrical precipitating system, the combination with a treating chamber, of a discharge electrode positioned therein and having a plurality of flame-emitting openings positioned below the electrode surface and a member of refractory material positioned to receive the flame blasts.

8. In an electrical precipitating system, the combination with a treating chamber, of a discharge electrode positioned therein and having an annular recess and a plurality of openings in a wall of said recess and a ring of refractory material located in said recess. v

9. In an electrical precipitating system, the combination with a treating chamber, of a discharge electrode positioned therein and having an annular recess and a ring of refractory material located in said recess, a plurality of flame-emitting openings being provided in the walls of said recess.

10. In 'an electrical precipitating system,

the combination with a treating chamber, of a discharge electrode positioned therein and having an annular recess and a ring of refractory material located in said recess, a plurality of rows of flame-emitting openings being provided in the walls of said recess respectively above and below said ring.

ll. A discharge electrode having a plurality of openings positioned entirely below the electrode surface and adapted to emit flame.

l2. A discharge electrode having an annular recess, a plurality of openings in a wall of said recess and refractory material located in said recess.

13. A discharge electrode having a plurality of annular recesses, a plurality of openings in the walls of said recesses and a plurality of rings of refractory material positioned in the respective recesses.

la. A discharge electrode having an annular recess and a plurality of openings in the walls of said recess.

15. A discharge electrode having an annular recess, a plurality of rows of openings in the walls of said recess, and a ring of nonmetallic material located within said recess between said rows.

1.6. A discharge electrode having a plurality of openings adapted to emit flame and refractory material positioned near said openings.

In testimony whereof, I have hereunto subscribed my name this 28th day of Feb., 1918. y

LEWIS WARRINGTON CHUBB. 

